Many patients with angina-like pain are found to have no significant coronary artery disease or spasm. We have recently shown that many such patients develop ischemia and exhibit abnormal arteriolar vasodilator reserve in response to pacing. The abnormality can be unmasked or exacerbated by cold pressor test or ergonovine infusion. Evaluation of left ventricular function by radionuclide angiography of 24 patients with abnormal vasodilator reserve demonstrated that the majority of these patients develop abnormalities of left ventricular function during exercise.